these are some nice lists so far, have to check some of these out. My additions;
Space.Above and Beyond. Late 80's sfi, Marines in space.
Robot Chicken. Some of the funnest stop motion on tv, oh the uses and abuses of my childhood.
Gunslinger Girl. Killer Italian cybernetic tweens. Well drawn, the background details are quite nice.

There are a lot of shows that I really enjoy, but here are some of my favorites:

Red Dwarf: British Sci Fi Comedy for the Win!
Avatar the Last Airbender: Best Cartoon series in a long time!
Star Trek Voyager: I watched this when I was a kid, it was my first Trek, and you never forget your first!
Grimm: Like It has that occulty feel to it I love. Kinda like Call of Cthulhu without the Cthulhu
Once Upon a Time: My guilty girly show
Up All Night: A lot of fun
Terra Nova: I'm so pissed this was cancelled! I still want to do a TN themed guard army
SHIN CHAN!: Incredibly stupid and irresistably funny.
Beavis and Butthead: I am Cornholio! Do you have TP?
Venture Brothers: Hilarious
Neon Genesis Evangelion: An anime classic
Cake Boss: I love this show! I keep hoping to see him do a Warhammer cake, and if I win the lottery he will...
NOVA: Gotta get my geology/science porn!
National Geographic: More geology/science porn!
How the Earth Was Made: Even more Geology Porn!
Invader Zim: Enough said
Life (The crime show, not the science one. I haven't seen that one yet)
Family Guy
American Dad

So yeah, I listed too many but those were the ones I could think of right now

Battlestar Galactica- awesome show loved the ending too
The Wire- best cop show ever, Omar is one of the greatest TV creations.
League of Gentlemen- hilarious twisted
The Thick of It- sharp, witty, satirical and relevant. British humour is superior
Im Alan Partridge- enough said
Anything by Chris Morris- brave, challenging, gross but always hilarious sod the royals he is a national treasure
Red Dwarf- watched this as a child but never got any of the jokes until much later
Black Adder- who needs history lessons
Lost- high concept crack, had to see it all through.
X-Files- favourite show of all time
Anything by Brian Cox, Patrick Moore and Carl Sagan- we are all stardust